Inconsistency about blanks wrt list tightness

[eureton]

The definition of blank line doesn't clarify scope:

A line containing no characters, or a line containing only spaces (U+0020) or tabs (U+0009), is called a blank line.

In other words, it's not clear whether the line scope is the document or the surrounding block element. Consider the snippet below:

- 
  abc

The latter interpretation classifies the line as blank wheres the former doesn't.

Farther down, Example 278 complicates matters further because the prose assumes the latter interpretation:

[...] some list items that start with a blank line but are not empty

whereas dingus implements the former (i.e. produced list is marked tight).

Which of the two is correct?

[wooorm]

But like, extending your reasoning for seeing blank lines as ambiguous here to some other language in the spec, such as for headings, would also make - # is this a heading? “ambiguous”.

I’m not sure what language change you propose, but I’d say the fact that containers include “lines” is adequately explained in the respective sections on those containers themselves: block quotes, list items.

[eureton]

@wooorm I have proposed no change.

My post concludes with a question. What gets corrected (spec text or dingus implementation) depends on the answer, which I don't have.

[wooorm]

L1 in your example is not a blank line to the whole document. To the list item, it is a blank line.

I’m not seeing where the spec text and dingus are at odds with each other?

[eureton]

I see now where my confusion comes from. I was mistaking the scope implied by the tightness definition:

A list is loose if any of its constituent list items are separated by blank lines

This makes

- abc
- 
  xyz

indeed tight, because L2 is blank to the item, but not to the list.